[SMACK] Label xwalk binaries with User domain

*In order to make all xwalk binaries running with same User domain
 label, we enforce "exec_label" property for them.
[Android] Add test case for getUrl().

This patch is to add test case for getUrl().
Open a url, get the url on ui thread, compare it with the expected.
Adapt user check to multi user architecture.

BUG:https://crosswalk-project.org/jira/browse/XWALK-1649

Change-Id: I2e38c4582e7b0bf1a024ffdad22d1bd14056bb11
Signed-off-by: Baptiste DURAND <baptiste.durand@open.eurogiciel.org>
[Android] Add test case for getTitle().

This patch is to add test case for getTitle().
Open a url, get the title on ui thread and compare it with the expected
result.
[Android] Apk will crash when set ‘undefined’ arch option

To filter out invalid values for option "arch".

BUG=https://crosswalk-project.org/jira/browse/XWALK-1618
[Tizen] Enable NaCl/PNaCl for 32bit build

Summary of changes:
============
* Enable nacl build and packaing in crosswalk.spec
* Unify GetXWalkDataPath for Tizen (service and non-service)
* Add native_client in source tarball

How to test:
============
On linux
$ cd <nacl_sdk_dir>/pepper_canary/example
$ TOOLCHAIN=pnacl make serve

On Tizen device or VM:
$ xwalk http://<your_linux_host>:5103/demo/flock/index.html?tc=pnacl

BUG=XWALK-1339
[Tizen] Fail to launch the "Webapi/Runtime" component

The issue occurred because EP file descriptor was attempted
to pass before is was initialized (before EP actually started).

BUG=XWALK-1432
[Android] Post onRsourceLoadStarted on UI thread

The shouldInterceptRequest method which invokes onRsourceLoadStarted
is called from IO thread, and onResourceLoadStarted must be called
from UI thread, since XWalkResourceClient.onLoadStarted is called
by it in chain.

BUG=XWALK-1695
Merge pull request #1934 from wuhengzhi/getTitle_test

[Android] Add test case for getTitle().
Merge pull request #1938 from pozdnyakov/XWALK-1432

[Tizen] Fail to launch the "Webapi/Runtime" component
Fix processing of the Manifest 'start_url' member

Fix processing of the Manifest 'start_url' member
after resolving an ambiguousness in the spec
https://github.com/w3c/manifest/pull/200/files

From now 'start_url' manifest key is an application
entry point.

So far 'start_url' cannot contain only a relative URL
(the resulting URL is constructed using the path to
the manifest file as a base URL:
http://w3c.github.io/manifest/#dfn-steps-for-processing-the-start_url-member)

External URLs handling should be clarified in the spec
further.
Merge pull request #1956 from pozdnyakov/start_url

Fix processing of the Manifest 'start_url' member
Merge pull request #1909 from PeterWangIntel/PR1618

[Android] Apk will crash when set ‘undefined’ arch option
Merge pull request #1914 from halton/nacl_tizen

[Tizen] Enable NaCl/PNaCl for 32bit build
Bump version to 7.35.139.0
Merge branch 'master' of github.com-crosswalk:crosswalk-project/crosswalk
Merge pull request #1948 from xingnan/1695

[Android] Post onRsourceLoadStarted on UI thread
Merge pull request #1935 from wuhengzhi/getUrl_test

[Android] Add test case for getUrl().
[Android] Add test case for clearCache().

This patch is to add test case for clearCache().
Request the url from TestWebServer, record the hit count to
webserver and compare the count with the expected number.
Drop "Main document" support

Spec: http://www.w3.org/2012/sysapps/app-lifecycle/#a-single-entry-point-to-the-application
SSIA. This patch removes the related functionality and tests.
Application class required quite deep modification, now it is inheriting
'content::RenderProcessHostObserver' to watch RPH lifecycle.